<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport"
      content="width=device-width, initial-scale=1, maximum-scale=1, minimum-scale=1, user-scalable=no">
    <title>Hello World!</title>
    <style>
      #rightTop {
        position: absolute;
        z-index: 100;
        width: 400px;
        height: 400px;
        right: 10px;
        top: 10px;
        border-radius: 8px;
        box-shadow: 0 0 4px rgba(0, 0, 0, .3);
        background: white;
      }
    </style>
  </head>
  <body>
    <div id="rightTop"></div>
    <div id="cesiumContainer"></div>
  </body>
</html>